You just posted in a year old topic.^^
Anyways, if you cant get the package via the “apt update” then it simply means that that apache package isnt in your used repos.
You can add additional repos for that, like sury his repos. He got one for apache2.
On Debian and Ubuntu it is generally safe to upgrade Apache as long as the new packages use the same paths and satisfy all the same dependencies.
The custom suexec makes it tricky on CentOS, but Debian/Ubuntu have a configurable suexec, so we use the standard OS Apache version.
However, I do not recommend using other packages. They don’t receive the same testing/vetting as the OS standard packages and are rarely as well-maintained. It is likely a relatively higher security risk to run a third party package. You should have a really damned good reason before using packages from other source.